The role of verapamil and SL-327 in morphine- and ethanol-induced state-dependent and cross state-dependent memory

Our results show that amnestic effects of morphine (10.0 mg/kg, s.c.) and ethanol (1.0 g/kg, i.p.) can be reversed by pre-test administrations of morphine (10.0 mg/kg, s.c.), ethanol (1.0 g/kg, i.p.) and nicotine (0.1 mg/kg, s.c.), indicating morphine and ethanol SDM, as well as morphine-ethanol, morphine-nicotine, ethanol-morphine and ethanol-nicotine cross SDM. Pre-test co-treatment of verapamil (10.0 mg/kg, i.p.) with morphine/ethanol/nicotine increased all investigated SDM and cross SDM effects. Pre-test co-treatment of SL-327 (10.0 mg/kg, i.p.) diminished morphine- and ethanol-induced SDM along with the cross effects except ethanol-morphine cross SDM. In conclusion, SDM depends on ERK1/2 activation and also verapamil affects this type of memory, although the exact mechanism of its cognitive action has not been investigated in this study.